The present invention relates to a color display system to be installed in stadiums, arenas, or streets for displaying images, characters and/or other patterns in colors by controlling a matrix of triads of light-emitting elements capable of emitting three primary colors with electric signals.
Known electric display systems installed in stadiums, arenas, streets or other public facilities and spaces comprise a matrix of incandescent lamps controlled by electric signals for displaying characters, images, and/or other patterns in monochromatic tones. As long as only characters are to be displayed, monochromatic display systems are usually satisfactory. However, monochromatic display systems have proven unattractive if images or graphic patterns are to be displayed thereon. To cope with this problem, there has been developed in the recent past a system composed of a matrix of three-primary triads of light-emitting elements for displaying colored images. Where only the colors of the light-emitting elements are to be displayed, the color display system is subjected to no technical difficulty since the density of light-emitting elements per unit area is not required to be increased. Where any images are to be displayed in natural colors by mixing the three primary colors, however, the light-emitting elements have to be packed at a much higher density, resulting in a variety of technical difficulties to be solved. More specifically, a color display system capable of displaying images and graphic patterns in various colors by mixing the three primary colors requires that about thirty to ninety thousand light-emitting elements be packed at an increased density such as at a pitch or inter-element interval of about 22 to 45 mm. Such a color display system is disadvantageous in that it is quite large in scale, is highly difficult to install, and a large amount of heat will be generated by the matrix of light-emitting elements.
One electric color display system which has heretofore been developed comprises a number of bar-shaped parallel display units each composed of an array of light-emitting elements. Two adjacent display units serve as one set of triads of light-emitting elements of three primary colors. Therefore, two separate trains of electric signals have to be applied to the display units in each triad set, thus requiring a complex wiring arrangement. Since there are required at least as many lead wires as there are light-emitting elements, a large number of cables are necessary for connection of the light-emitting elements to a control circuit disposed behind the display units. It is a tedious and time-consuming task to lay and connect those cables. The cables need a large installation space behind the display units and result in a substantial increase in the cost. In addition, only a limited space is available for the installation of a ventilator for cooling the light-emitting elements.
Another prior color display unit is in the form of a rectangular parallelopied supporting on its face a matrix of light-emitting elements. Such a display unit, particularly those light-emitting elements close to the center thereof, cannot sufficiently be cooled for heat dissipation by a ventilator positioned behind the display unit.